1. Field of the Invention
The invention described herein pertains to the processing of natural gas for removal of contaminants such as liquid particles, solid particles, water, carbon dioxide, hydrogen sulfide or other undesirable components by absorption into a suitable liquid. The field of search was 261 "GAS AND LIQUID CONTACT APPARATUS", with possible subclasses 19 "Fluid Distribution", 20 "Systems", 75 "Contact Devices", 94 "Porous Mass", 100 "Porous Sheet", 101 "Surface Contact", 106 "Liquid Flow", and 112 "Film". The invention is believed to fall in the category 261.20.
2. Description of the Prior Art
Contactor devices, including contactor towers have been used for several years as a means for removing undesirable elements from natural gas streams. Contactor towers are pipes through which gas is circulated and liquids or solids are put into contact with the gas to absorb or react with unwanted components. Towers can be roughly divided into four categories, liquid filled, random packing, trays, and structured packing.
Random packing is an application of thin film technology and typically consists of balls, shapes, rings, etc. which are dumped into a tower for a bed over which a suitable liquid is poured. The liquid will theoretically spread out into a thin film covering the packing and giving a large surface area of liquid exposed to the gas which passes up through the bed.
Liquid towers are tanks filled with a liquid chemical solution through which the gas bubbles. These units are relatively large, heavy, and can have significant carryover problems with higher flow rates. If the liquid is not regenerated, the resultant mixture may be considered as hazardous waste and may present disposal problems.
Tray towers consist of one or more trays having various openings through which the gas flows upwards and the liquid passes down from tray to tray. Typical problems with tray type towers are plugging of the openings, channeling of the gas through the trays, loss of downcomer seal, and carryover due to foaming. Foaming is a particular problem because many of the chemical solutions in use have a tendency to foam and the bubbling action of the gas as it passes through the trays creates ideal conditions for foam formation. Due to the inefficiency of the trays, the towers tend to be relatively large and heavy, particularly when higher operating pressures are involved.
Structured packing is an attempt to provide a thin film approach similar to that provided by the random packing but with control over the path of both the gas and the liquid. Most of the structured packing elements in use should be considered as semi-random packing since they do not truly allow for control of the gas flow through the unit. Structured packing also tends to be hard to fabricate and may have a tendency to plug up if there is any amount of debris in the gas stream or the gas has components which may tend to plate out on contact surfaces.
In most practical applications of random packing, tray towers and structured packing, both the gas and the liquid tend to find preferred paths through the bed and full utilization is not achieved.